Brakes get grabby the more you drive

[Gas Pig]

Ok once again the 74 problem child is back at it!

The more I drive the truck the brakes get grabby and start to squeak. You let the truck sit a while the brakes feel better.

I have a front disc chevy disc brake on version with drums on the back. Everything is new except the vacuum booster. It’s a used aftermarket booster, that seemingly to work fine but could that be my problem? Or simply take everything off and brake clean the components?

Thanks Jeff

 

[Timmy390]

Anytime I hear chevy conversion and brake issue I thing sticking calipers as in not enough ground off. Heat builds metal expands.....sticking calipers.

Tim

 

[Wild horse 75]

Look for contamination on the shoes. Heat will draw it to the surface. Could be from your fingers during the install.

 

[Gas Pig]

I’ll double check the caliper clearance issue. You, know you grind the crap out of the knuckle and it’s still not enough! lol

While I have it off the ground and apart and clean all the brake contact surfaces again!

Thanks guys!

 

[Slowleak]

You may want to check the clearance between your master cylinder piston and the pushrod coming out of your booster. You need a little gap there or as the calipers and brake fluid heat, fluid expansion will cause the brakes to drag and feel “grabby”. If the rod is adjustable, you can back it off a little and test it, or try a spacer between the booster and master cylinder.

 

[73azbronco]

did you bed the brakes in?

 

[phred]

Another problem is the chinesium rebuilt calipers will often have phenolic pistons which sometimes swell with heat making them stick. Had that happen on the tail of the dragon.

 

[Gas Pig]

You may want to check the clearance between your master cylinder piston and the pushrod coming out of your booster. You need a little gap there or as the calipers and brake fluid heat, fluid expansion will cause the brakes to drag and feel “grabby”. If the rod is adjustable, you can back it off a little and test it, or try a spacer between the booster and master cylinder.

I checked today and it appears that the clearance seems good between the knuckles and calipers… about 1/4”?

I’ll double check the rod gap from the booster to master cylinder when I home from work.

 

[Gas Pig]

Another problem is the chinesium rebuilt calipers will often have phenolic pistons which sometimes swell with heat making them stick. Had that happen on the tail of the dragon.

I have seen that before but I’m pretty sure both of these are steel pistons on the calipers. But I will look again when I clean the brakes.

 

[cldonley]

Another problem is the chinesium rebuilt calipers will often have phenolic pistons which sometimes swell with heat making them stick. Had that happen on the tail of the dragon.

You took your rig to Deal's Gap? Sweet.

 

[Gas Pig]

did you bed the brakes in?

Yep, I think I bled the brakes and put a quart of fluid through them. But I’m willing to bleed them again for safe measures just to be sure.

 

[mrdrnac]

I think 73AZ Bronco meant:

• The break bedding in procedure is a process of quickly heating and cooling the brakes in a repeated fashion, and while doing so it deposits a layer of pad material on the rotor surface. Temperature needs to be slowly heated to max use, which will create a smooth, even pad transfer.

 

[4xfun]

You mentioned all new parts. Were the rubber hoses new. Old hoses can degrade on the inside and the swelling limits the ability of the fluid to move back to the master cylinder. The same can be said for the master cylinder. If there is trash in the system, it can block an internal valve..

 

[EPB72]

If there is nothing causing any drag , I would not rule out you just have a set of defective brake pads, as a tech and handled/replaced thousands of brakes it does happen occasionally, so consider replacing:warranty pads out ,, do you think it’s front or rear? Also if you have an infrared thermometer check temps of rotors drums after driven, post temps

 

[73azbronco]

bed the brakes, long version above, short version, hit 65 or so, slam brakes on to stop, like intermittent skid but keep wheels turning, thats the point, repeat two more times, then, brakes have been bedded and all deposits are gone. I have to do it every few weeks on a new cherokee after it goes through car wash and gets wax on the disk.

Car dealers love to say you need brake job if brakes chatter. Nope, bed brakes in, fixed.

 

[phred]

You took your rig to Deal's Gap? Sweet.

Yep more than once. That time I drove it back to Townsend with no brakes.

 

[Gas Pig]

bed the brakes, long version above, short version, hit 65 or so, slam brakes on to stop, like intermittent skid but keep wheels turning, thats the point, repeat two more times, then, brakes have been bedded and all deposits are gone. I have to do it every few weeks on a new cherokee after it goes through car wash and gets wax on the disk.

Car dealers love to say you need brake job if brakes chatter. Nope, bed brakes in, fixed.

Yeah I completely miss read the “have you bed the brakes”… bed to bled! lol

Nope I haven’t hit the brakes hard yet. This truck is still building my trust and I have been chasing one thing after another. That is what happens when you take to long to build your own truck. Oh well but I certainly will try that when I get the chance. Before I do that should I bother brake cleaning them first?

 

[Gas Pig]

If there is nothing causing any drag , I would not rule out you just have a set of defective brake pads, as a tech and handled/replaced thousands of brakes it does happen occasionally, so consider replacing:warranty pads out ,, do you think it’s front or rear? Also if you have an infrared thermometer check temps of rotors drums after driven, post temps

I can try the swaping the front pads. I did experience that in the back with the shoes. One side was get smoking hot while the other side was cool. I changed shoes (used ones but fairly new), The heat problem went to the other side. Then I did a mix and match and they balanced with the temp. But not wanting mix and match sets I went and bought Bosch and they seem much better. The squeak could be coming from the rear but had to tell because it on passenger side. The pain of it is the also adjusting the rear because it factory possi… kind of tricky to adjust them evenly. Any thoughts on that as well!

 

[Wild horse 75]

If your drums don’t have a lip you can adjust them till it’s hard to slip them on. That way you don’t have to rotate them to check drag.

 

[cldonley]

Yep more than once. That time I drove it back to Townsend with no brakes.

Went twice-once on the bike and once in the Mustang. Great fun. Driving around with no brakes-not fun.